Ever since the internal combustion engine was commercially developed, it was necessary to treat the exhaust coming from the engine. Such treatment initially included sound suppression, but in the mid 1970's, included exhaust aftertreatment devices in the form of catalytic converters to minimize emissions considered harmful by the Environmental Protection Agency (EPA). With the application of EPA regulations to compression ignition or diesel engines, the process of aftertreatment became more complex since typically the devices included a diesel oxidization catalyst (DOC) and a downstream diesel particulate filter (DPF). The addition of the size and weight of these components has made the mounting of the exhaust aftertreatment device on the frame of a vehicle significantly more difficult. It is of course due to additional weight but, beyond that, the variations in temperature require accommodations for thermal expansion. The process of mounting the exhaust aftertreatment device becomes more difficult because it is necessary not to have any gas leaks.
Typically, exhaust aftertreatment devices carry on the construction of the mufflers and automotive aftertreatment devices in providing stamped steel or fabricated assemblies. This construction emulates the construction of mufflers in having formed end plates and interconnecting elements made of sheet metal and appropriately welded together. The problem with this type of construction is that the increased physical loads and thermal loads coupled with the necessity to properly mount it to a vehicle frame causes increased deflection and with it the increased possibility of leaks and/or structural failure.
Another problem with a fabricated structure is that the orientation of the device is fixed upon completion of the welds. No further flexibility is available to accommodate different spatial positions of the exhaust conduits leading to and away for the device.
Accordingly, what is needed in the art is an exhaust aftertreatment device construction enabling a robust and efficient mounting with flexibility.